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This paper describes a uniform Hardware-In-the-Loop (HiL) test rig for the different types of Electronic Braking System (EBS). It is applied to both modular testing and integrated testing. This test rig includes a vehicle dynamic model, a real-time simulation platform, an actual brake circuit and the EBS system under test. Firstly, the vehicle dynamic model is a highly parameterized commercial vehicle model. So it can simulate different types of commercial vehicle by different parameter configurations. Secondly, multi-types of brake circuit are modeled using brake components simulation library. So, it can test the EBS control unit independently without the influence of any real electro-pneumatic components. And a software EBS controller is also modeled. So it can test the algorithm of EBS offline. Thirdly, all real electro-pneumatic components without real gas inputted are connected to the real-time test platform through independent program-controlled relay-switches.

The ever-growing number of interacting electronic vehicle control systems requires new control algorithms to manage the increasing system complexity. As a result, torque-based control architecture has been popular for its easy extension as the torque demand variable is the only interface between the engine control algorithms and other vehicle control systems. Under the torque-based control architecture, the engine and AT coordinated control for upshift process is investigated. Based on the dynamics analysis, quantitative relationship between the turbine torque of HTC and output shaft torque of AT has been obtained. Then the coordinated control strategy has been developed to smooth the torque trajectory of AT output shaft. The designed control strategy is tested on a powertrain simulation model in MATLAB/Simulink and a test bench. Through simulation, the shift time range in which the engine coordinated control strategy is effective is acquired.

A new method for driving the hydraulic free piston engine is proposed. This method achieves the compression stroke automatically rather than special recovery system. Principle of hydraulic differential drive free-piston engine is analyzed and the control strategy of this novel hydraulic driving engine is also introduced. Then energy balance method is used to design the main parameters of the novel engine. High pressure and secondary high pressure of the hydraulic system are constrained by the combustion parameters and therefore parameters are analyzed. In order to verify the effectiveness of energy balance method, the mathematical model is established based on the piston force analysis and engine working principle. The transient results of dynamics are obtained through simulation. In addition, the effectiveness of the simulation is proofed by dimensionless analysis. It indicates that energy balance method realizes the basic performance of hydraulic free piston engine.

The output power of a turbocharged diesel engine will decrease and the maximum torque point in the full load torque map will move backwards when the engine is operating at plateau.

Brake squeal is a complex dynamics instability issue for automobile industry. Closed-loop coupling model deals with brake squeal from a perspective of structural instability. Friction characteristics between pads and disc rotor play important roles. In this paper, a closed-loop coupling model which incorporates negative friction-velocity slope is presented. Different from other existing models where the interface nodes are coupled through assumed springs, they are connected directly in the presented model. Negative friction slope is taken into account. Relationship between nodes’ frictional forces, relative speeds and brake pressure under equilibrant sliding and vibrating states is analysed. Then repeated nodal coordinate elimination and substructures’ modal coordinate space transformation of system dynamic equation are performed. It shows that the negative friction slope leads to negative damping items in dynamic equation of system.

The dynamic properties of disc rotor play important role in the NVH performance of a disc brake system. Disc rotor in general is a centrosymmetric structure. It has many repeated-root modes within the interested frequency range and they may have significant influence on squeal occurrence. A pair of repeated-root modes is in nature one vibration mode. However, in current complex eigenvalue analysis model and relevant analysis methods, repeated-root modes are processed separately. This may lead to contradictory result. This paper presents methods to deal with repeated-root modes in substructure modal composition (SMC) analysis to avoid the contradiction. Through curve-fitting technique, the modal shape coefficients of repeated-root modes are expressed in an identical formula. This formula is used in SMC analysis to obtain an integrated SMC value to represent the total influence of two repeated-root modes.

With the development of advanced ABE fermentation technology, the volumetric percentage of acetone, butanol and ethanol in the bio-solvents can be precisely controlled. To seek for an optimized volumetric ratio for ABE-diesel blends, the previous work in our team has experimentally investigated and analyzed the combustion features of ABE-diesel blends with different volumetric ratio (A: B: E: 6:3:1; 3:6:1; 0:10:0, vol. %) in a constant volume chamber. It was found that an increased amount of acetone would lead to a significant advancement of combustion phasing whereas butanol would compensate the advancing effect. Both spray dynamic and chemistry reaction dynamic are of great importance in explaining the unique combustion characteristic of ABE-diesel blend. In this study, a semi-detailed chemical mechanism is constructed and used to model ABE-diesel spray combustion in a constant volume chamber.

In this paper, a new method for the driving of the hydraulic free piston engine (HFPE) is proposed. Hydraulic differential drive achieves the compression stroke automatically rather than special recovery system, which has a great influence on the engine dynamic performance. The purpose of this paper is to solve the key operation and control problems for HFPE to commix fuel with air. HFPE adopts two-stroke loop-scavenging and semi-direct injection. The semi-direct injection nozzle is located in the liner wall inside the main intake port, with the axes oriented towards the piston at the Bottom Dead Center (BDC). Different scavenging pressures and injection angles result in different impacts on the mixture of fuel and air in the cylinder. This study analyzes the changes of the combustion heat release rate by simulation.

The study of mechanical properties special in the characteristics of elastic element is a challenging task for vehicle industry. Since torsion bar spring acts as an important part of elastic element, and improves performance of torsion bar spring is of great concern. The effects of the torsion bar spring pre-setting precision on the presetting performance are presented. Based on elastic-plastic theories, the algebraic model of torsion bar spring is established to analyze the stress, torque and residual stress under the yield and plastic conditions in pre-setting process. Then, the stress and strain states of various torsion bar springs in different conditions are simulated using the validated finite element model in ABAQUS software. The simulation results show the effects of torsion error on the pre-setting performance are less than 5% in the pre-setting process.

Closed-loop coupling model, based on complex eigenvalue analysis, is one of the most popular and effective methods for brake squeal analysis. In the model, imaginary coupling springs are used to represent the normal contacting force between coupled nodes. Unfortunately, the physical meaning of these coupling springs was seldom discussed and there’s no systematic method to determine the value of spring stiffness. Realizing this problem, this paper, based on finite element model and modal synthesis technique, develops a new closed-loop coupling disc brake squeal model without introducing imaginary coupling springs. Different from the traditional model where two nodes at coupling interface are connected through a spring, these node-pairs in the new model are assumed to remain in tight contact during vibration. Details of the model, including force analysis, coordinate reduction and transformation and complex eigenvalue decomposition are given in this paper.

In this paper, a new-type balanced opposed-piston two-stroke (OP2S) gasoline direct injection (GDI) engine is developed by Beijing Institute of Technology. OP2S-GDI engine has some potential advantages such as simple structure, good balance, compact, high power density and thermal efficiency. The structural feature of OP2S-GDI engine leads to the performance difference compared with conventional engines. In order to study and verify the characteristics of this kind of engine, the dynamics characteristics and design scheme of opposed crank-connecting rod mechanism, in-cylinder scavenging process, mixture formation and combustion process are investigated. The influence of parameters on engine performance is investigated, including opposed-piston motion phase difference, intake and exhaust port timing, injection and ignition timing.

The hydraulic free piston engine is a complex mechanical-electro-liquid system, in order to simplify the complex system of the single hydraulic free piston engine, a new method for the driving of hydraulic free piston engine is proposed. Hydraulic differential drive achieves the compression stroke automatically rather than special recovery system. The structure and principle of hydraulic differential drive free-piston engine are analyzed and the mathematical model is established based on the piston force analysis and the hydraulic system working principle. In addition, the control strategy of this novel hydraulic driving engine is also introduced. Finally, the transient results of dynamics are obtained through simulation. Then we compare our results to the ones from the hydraulic free piston engine made by the company Innas.

The cylinder-by-cylinder variations have many bad impacts on the engine performance, such as increasing the engine speed fluctuation, enlarging the torsional vibration and noise. To deal with this problem, the impact mechanism of cylinder-by-cylinder variations on low order torsional vibration has been studied in this paper, and subsequently a new individual cylinder control strategy was designed by processing the instantaneous crankshaft rotation speed signal, detecting the cylinder-by-cylinder variation and using feed-back control. The acceleration characteristics of each cylinder in each engine cycle were compared with each other to extract the variation index. The feed-back control algorithm was based on the regulation of the fuel injection according to the detected variation level.

This paper investigates the scavenging process, in-cylinder gas motion in an opposed-piston two-stroke diesel engine and compares the results of in-cylinder gas motion to those of a uniflow-scavenged two stroke conventional engine using computational fluid dynamics engine models. The effect of piston motion profile of OP2S on the scavenging performance was discussed and its optimization was developed. Subsequently, CFD simulation on full load scavenging process was conducted at the same intake pressure and simulation at 2500rpm showed an optimum scavenging performance evaluated by delivery ratio, trapping efficiency and scavenging efficiency. Enhanced axial velocity and average turbulence kinetic energy around minimum volume center were found for OP2S diesel engine compared to the conventional two-stroke diesel engine.

Wiper noise generated in the wiping process is one of the main influence factors affecting the driving comfort. Since the dynamic contact pressure of the contact between a blade and a windshield glass is difficult to be measured, it is also difficult to predict the degree of the wiper noise. In this paper, in the view of the reversal noise problem of a passenger-vehicle windscreen wiper system, the system dynamic models of the both wipers on the sides of the driver and copilot were built as considering the blade deformation and the elastic contact between the blades and the windscreen glass, including the crank pivot, the four linkage mechanism, the wiper blades, the wiper arms and the windscreen glass. The motion of the wiper system and the pressure distributions between the blades and the windscreen glass were analyzed under the half-dry condition.

Variable nozzle turbine (VNT) adjusts the openings of its nozzles to insure the required flow at throat area, which broadens the operating range of the turbine, and improves the matching relationship between the turbocharger and the engine. But the changes of nozzle openings have significant influence on the flow field structure of downstream radial turbine. To evaluate this effect, the leakage flow through nozzle clearance in various nozzle openings were simulated by unsteady computational fluid dynamic (CFD). Meanwhile, the interaction between nozzle clearance leakage flow and nozzle wake were investigated to reveal its effects on aerodynamic losses and forced responses for downstream rotor. The results showed that the changes of nozzle openings not only affect the interaction between nozzle leakage flows and wake significantly, but also affect aerodynamic performance of the rotor and the blade forced response.

This paper proposes an effective nonlinear bicycle model including longitudinal, lateral, and yaw motions of a vehicle. This bicycle model uses a simplified piece-wise linear tire model and tire force tuning algorithm to produce closely matching vehicle trajectory compared to real vehicle for wide vehicle operation ranges. A simplified piece-wise tire model that well represents nonlinear tire forces was developed. The key parameters of this model can be chosen from measured tire forces. For the effects of dynamic load transfer due to sharp vehicle maneuvers, a tire force tuning algorithm that dynamically adjusts tire forces of the bicycle model based on measured vehicle lateral acceleration is proposed. Responses of the proposed bicycle model have been compared with commercial vehicle dynamics model (CarSim) through simulation in various vehicle maneuvers (ramp steer, sine-with-dwell).

A coupled vibro-acoustic of a compressor modeling process was demonstrated for predicting the acoustic radiation from a vibrating compressor structure based on dynamic response data. FEM based modal analysis of the compressor was performed and the result was compared with experimental data, for the purpose of validating the FE model. Modal based force response analysis was conducted to calculate the compressor's surface vibration velocity on radiating structure, using the load which caused by mechanical excitation as input data. In addition, due to the coolant had oscillating gas pressure, the gas pulsed load was also considered during the dynamic response analysis. The surface vibration velocity solution of the compressor provided the necessary boundary condition input into a finite element/boundary element acoustic code for predicting acoustic radiation.

High fidelity mathematical vehicle models that can accurately capture the dynamics of car suspension system are critical in vehicle dynamics studies. System identification techniques can be employed to determine model type, order and parameters. Such techniques are well developed and usually used on linear models. Unfortunately, shock absorbers have nonlinear characteristics that are non-negligible, especially with regard the vehicle's vertical dynamics. In order to effectively employ system identification techniques on a vehicle, a nonlinear mathematical shock absorber model must be developed and then coupled to the linear vehicle model. Such an approach addresses the nonlinear nature of the shock absorber for system identification purposes. This paper presents an approach to integrate the nonlinear shock absorber model into the vehicle model for system identification.

This paper presents a control system development for a yaw motion control of a vehicle-trailer combination using the integrated control of active front steer (AFS) and differential brake (DB). A 21 degree of freedom (dof) vehicle-trailer combination model that represents a large SUV and a medium one-axle trailer has been developed for this study. A model reference sliding mode controller (MRSMC) has been developed to generate the desired yaw moment. Based on the understanding of advantages and limitations of AFS and DB, a new integrated control algorithm was proposed. The simulation result shows that integrated control of AFS and DB can restrain the trailer's oscillation effectively and shows less longitudinal speed drop and higher stable margin compared to the DB activated only case while maintaining the yaw stability.